Holographic laser scanning method and system employing visible scanning-zone indicators identifying a three-dimensional omni-directional laser scanning volume for package transport navigation

ABSTRACT

An improved 3-D omni-directional holographic laser scanning system including visible indicia specifying location of the 3-D scanning volume (and the 3-D omni-directional scanning pattern therein) that is visibly discernable to users of the system. Such visible indicia may be one or more visible light beams that provide a visible light pattern characterizing location of the 3-D scanning volume (and the 3-D omni-directional scanning pattern therein). Alternatively, such visible indicia may be visible markings, such as reflective paint or reflective tape, affixed to a surface (over which objects are moved through the 3-D scanning volume) in a manner that characterizes location of the 3-D scanning volume (and the 3-D omni-directional scanning pattern therein). Such visible indicia may characterize location of the 3-D scanning volume (and the 3-D omni-directional scanning pattern therein) by providing an indication of the approximate location of the center of the 3-D scanning volume, of one or more edges of the 3-D scanning volume, and/or of any other portion of the 3-D scanning volume. Such visible indicia enable users to quickly identify the correct location of the 3-D scanning volume (and the 3-D omni-directional scanning pattern therein) when attempting to transport the object through the 3-D scanning volume, thus limiting unwanted scanning errors and increasing the productivity of the user, which represents decreased costs associated with the use of the holographic laser scanning

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation-in-Part of: U.S. application Ser. No.09/479,780 filed Jan. 7, 2000, which is a Continuation of U.S.application Ser. No. 08/940,561 filed Sep. 30, 1997, now U.S. Pat. No.6,112,990, which is a Continuation of U.S. application Ser. No.08/886,806 filed Apr. 22, 1997, now U.S. Pat. No. 5,984,185, which is aContinuation of U.S. application Ser. No. 08/573,949 filed Dec. 18,1995, now abandoned; U.S. application Ser. No. 09/505,239 filed Feb. 16,2000, which is a Continuation of U.S. application Ser. No. 08/854,832filed May 12, 1997, now U.S. Pat. No. 6,085,978; U.S. application Ser.No. 09/505,238 filed Feb. 16, 2000, which is a Continuation of U.S.application Ser. No. 08/949,915 filed Oct. 14, 1997, now U.S. Pat. No.6,158,659; U.S. application Ser. No. 09/047,146 filed Mar. 24, 1998;U.S. application Ser. No. 09/157,778 filed Sep. 21, 1998; U.S.application Ser. No. 09/274,265 filed Mar. 22, 1999; U.S. applicationSer. No. 09/275,518 filed Mar. 24, 1999; U.S. application Ser. No.09/305,896 filed May 5, 1999; U.S. patent application Ser. No.09/243,078 filed Feb. 2, 1999, U.S. application Ser. No. 09/442,718filed Nov. 18, 1999, and U.S. application Ser. No. 09/551,887 filed Apr.18, 2000.

BACKRGROUND OF INVENTION

1. Field of Invention

The present invention relates to holographic laser scanning systems thatproduce an omni-directional scanning pattern in a three-dimensional(3-D) scanning volume wherein users manually transport an object throughthe 3-D scanning volume to detect physical attributes of the object(such as detecting and decoding bar code symbols on surfaces of theobject).

2. Brief Description of the Prior Art

Handheld laser scanning systems typically form a single scan line whichmust be properly aimed over the surface of its intended target object.Handheld laser scanners such as those described in U.S. Pat. Nos.4,603,262 and 5,296,689 were developed that used a pointer beam (oraiming light) which is visible over the intended scan distance to aidthe user in aiming the handheld scanner (or orienting the targetobject).

Polygonal laser scanning systems generate a multi-directional scanpattern forming a scan volume which is typically not well-defined. U.S.Pat. No. 6,223,986 discloses a polygonal laser scanning system thatemploys a laser light source to generate a visible target (or image) inthe scan volume at a preferred location for placement of the article tobe scanned.

Handheld laser scanning systems and polygonal laser scanning systems aretypically limited to scanning applications that require a small scanvolume (because it is cost-prohibitive to use such systems toomni-directionally scan a large scan volume).

In contrast, laser scanning systems employing holographic opticalelements can be cost-effectively designed and manufactured to produce anomni-directional pattern through a large well-defined scanning volume(preferably with multiple scanning beams with varying depths of field inthe scanning volume). The present inventors have recognized thepotential to facilitate scanning in 3-D omni-directional holographiclaser scanning systems.

In 3-D omni-directional holographic laser scanning systems, such asMetrologic's HoloTrak® scanner products, it is often difficult for usersto locate the position of the 3-D scanning volume (and the 3-Domni-directional scan pattern therein) without looking directly into thescanner and thus exposing the user's eyes to potentially (or assumed)harmful laser scanning beams. The reason that the 3-D scanning volume(and the 3-D omni-directional scan pattern therein) is not readilyvisible is due to the high speed of the scanning beams and itsrelatively low intensity compared to ambient light.

When a user of such a system is required to manually transport an objectthrough the 3-D scanning volume (and the 3-D omni-directional scanningpattern therein) to detect physical attributes of the object (such asdetecting and decoding bar code symbols on surfaces of the object),unwanted scanning errors occur in the event that the user is unable toidentify the correct location of the 3-D scanning volume (and theomni-directional scan pattern therein) when attempting to transport theobject through the 3-D scan volume. Such unwanted scanning errors limitthe productivity of the user. Moreover, any time taken by a user inlocating the 3-D scanning volume limits the productivity of the user.Such limitations in user productivity represent increased costsassociated with the use of the laser scanning system. In addition, auser repetitively searching for the 3-D scanning volume of the systemcan potentially lead to repetitive motion strain and injury

Thus, there is a great need in the art for an improved holographic laserscanning systems that enables users to efficiently locate the 3-Dscanning volume (and the 3-D omni-directional scan pattern therein) ofthe 3-D omni-directional laser scanning system, while avoiding theshortcomings and drawbacks of prior art holographic scanning systems andmethodologies.

SUMMARY OF INVENTION

Accordingly, a primary object of the present invention is to provide anovel 3-D omni-directional holographic laser scanning-system that isfree of the shortcomings and drawbacks of prior art laser scanningsystems and methodologies.

Another object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that provides visibleindicia, visibly discernable by users of the system, characterizing thelocation of the 3-D scanning volume (and the 3-D omni-directional scanpattern therein) of the system, relative to the physical environment inwhich the system is installed and operated.

Another object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that provides visibleindicia characterizing the approximate location of the center, edges orother portion of the 3-D scanning volume (and the 3-D omni-directionalscan pattern therein) of the system.

Another object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that utilizes lowcost materials to provide visible indicia characterizing the location ofthe 3-D scanning volume (and the 3-D omni-directional scan patterntherein) of the system.

Another object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that utilizes avisible light pattern, which is preferably distinguishable from thescanning beam(s) of the system, to provide visible indiciacharacterizing the location of the 3-D scanning volume (and the 3-Domni-directional scan pattern therein) of the 3-D omni-directional laserscanning system.

Another object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that utilizes areadily-discernable visible light pattern to provide visible indiciacharacterizing the location of the 3-D scanning volume (and the 3-Domni-directional scan pattern therein) of the system.

Another object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that shines a visiblelight pattern on a surface over which the objects are moved through the3-D scanning volume to provide a visible indication of pointssubstantially corresponding to the boundary of the projection of the 3-Dscanning volume (and the 3-D omni-directional scan pattern therein) ontothe surface.

A further object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that uses the samelaser scanning beam(s) to detect properties of surfaces passing througha 3-D scanning volume and to provide visible indicia characterizinglocation of the 3-D scanning volume (and the 3-D omni-directional scanpattern therein) of the system.

A further object of the present invention is to provide a 3-Domni-directional holographic laser scanning system that provides visibleindicia characterizing location of the 3-D scanning volume (and the 3-Domni-directional scan pattern therein) of the system and provides anindication that the user has entered a region corresponding to the 3-Dscanning volume.

These and other objects of the present invention will become apparenthereinafter and in the Claims to Invention.

BRIEF DESCRIPTION OF DRAWINGS

For a more complete understanding of the present invention, thefollowing Detailed Description of the Illustrative Embodiment should beread in conjunction with the accompanying Drawings, wherein:

FIG. 1 is a schematic illustration of a 3-D omni-directional holographiclaser scanning system 100 wherein a laser light source 101 (such as aVLD) emits laser light beams (denoted I); a holographic laser scanningsubsystem 103 utilizes a plurality of holographic optical elements(preferably supported on a rotating disc) to direct portions (denotedI′) of these laser light beams to create an 3-D omni-directional scanpattern that defines a 3-D scanning volume 105; portions of thereturning (i.e., incoming) laser light beams (denoted I″) from the 3-Dscanning volume 105, which reflect off light reflective surfaces in the3-D scanning volume 105, are collected by the subsystem 103 and portions(denoted I′″) of the collected light are directed to photodetector(s)107 and signal processing and control circuitry 109 that capture andanalyze the collected light to identify properties (such as bar codesymbol) of surfaces (or objects) within the 3-D scanning volume 105.

FIG. 2(A) is a perspective front view of an illustrative embodiment ofan overhead 3-D omni-directional holographic laser scanning system 100′according to the present invention, including one or more light beams (4shown as 111A, 111B, 111C and 111D) that provide a visible light patterncharacterizing the location of the 3-D scanning volume 105′ (and the 3-Domni-directional scan pattern therein) of the system 100′.

FIG. 2(B) is a perspective bottom view of the overhead 3-Domni-directional holographic laser scanning system 100′ of FIG. 2(A)including at least one light production module (4 shown as 115A, 115B,115C and 115D) mounted to the bottom of the housing of the system 100′that provides the visible light pattern (for example, the four visiblelight beams 111A, 111B, 111C and 111D as shown) characterizing thelocation of the 3-D scanning volume 105′ (and the 3-D omni-directionalscan pattern therein) of the system 100′.

FIG. 3 is a perspective front view of an illustrative embodiment of anoverhead 3D omni-directional holographic laser scanning system 100″according to the present invention, including visible markings 112 thatare affixed to a surface 113 over which the objects are moved throughthe 3-D scanning volume 105″ and that provide visible indiciacharacterizing the location of the 3-D scanning volume 105″ (and the 3-Domni-directional scan pattern therein) of the system 100″.

FIG. 4(A) is a schematic illustration of a top view of an exemplaryholographic laser scanning system 100-A of the present invention, whichproduces an omni-directional laser scanning pattern having differentmulti-directional scan patterns at multiple focal zones (e.g., multiplefocal planes) in a 3-D scanning volume which are formed by five laserscanning stations indicated as LS1, LS2, LS3, LS4 and LS5 arranged abouta sixteen-facet holographic scanning disc 130.

FIG. 4(B) is a schematic illustration of one (LS1) of the laser scanningstations of the holographic laser scanning system 100-A of the presentinvention as illustrated in FIG. 4(A) including a laser beam productionmodule 147A mounted on an optical bench; and a beam folding mirror 142Aassociated with the laser scanning station L1, having a substantiallyplanar reflective surface and is tangentially mounted adjacent to theholographic scanning disc 130.

FIG. 4(C) is a schematic illustration of a cross-section of theholographic laser scanning system 100-A of the present invention asillustrated in FIGS. 4(A) and 4(B), wherein facets of rotating thescanning disk 130 diffract incident light beams (produced from the laserbeam production module 147A) and directs the diffracted light beams ontothe associated light bending mirrors 142A, which directs the diffractedlight beams through the 3-D scanning volume, thereby producing a 3-Domni-directional scanning pattern with multiple focal zones; at leastone photodetector (e.g. a silicon photocell) 152A is mounted along thecentral reference plane of the laser scanning station LS1, above theholographic disc 130 and opposite its associated beam folding mirror142A so that it does not block or otherwise interfere with the returning(i.e. incoming) light rays reflecting off light reflective surfaces(e.g. product surfaces, bar code symbols, etc) during laser scanning andlight collecting operations; the electrical analog scan data signalproduced from the photodetector 152A (and other photodetectors 152B . .. 152E) is processed to detect properties (such as detecting anddecoding bar code symbols on surfaces of objects) of the surfaces; theparabolic light collecting mirror 149A of the laser scanning station L1is disposed beneath the holographic scanning disc 130, along the centralreference plane associated with the laser scanning station LS1; thelight collecting mirror 149A collects incoming light rays reflected offthe surfaces (e.g. bar code symbol affixed thereto) and passing throughthe holographic facet (producing the corresponding instant scanningbeam) onto to the parabolic light collecting mirror 149A; and focusessuch collected light rays through the same holographic facet onto thephotodetector associated with the laser scanning station.

FIG. 4(D) is a schematic illustration of the scanning disk 130 of theholographic laser scanning system 100-A of the present-invention asillustrated in FIGS. 4(A), 4(B) and 4(C). FIG. 4(E) is a schematicillustration of a laser production module for one (LS1) of the laserscanning stations of the holographic laser scanning system 100-A of thepresent invention as illustrated in FIGS. 4(A), 4(B) and 4(C) including:a visible laser diode (VLD) 101A, an aspheric collimating lens 51supported within the bore of a housing 53 mounted upon an optical bench143 of the module housing for focusing the laser light produced by theVLD 101A; a mirror 55, supported within the housing 53, for directingthe focused laser light produced by lens 51 to a multi-function lightdiffractive grating 57 supported by the housing 53; the multi-functionlight diffractive grating 57, which has a fixed spatial frequency and isdisposed at incident angle relative to the outgoing laser beam providedby the mirror 55, produces a primary beam that is directed toward thefacets of the rotating scanning disk 130; and the multi-function lightdiffractive grating 57 changes the properties of the incident laser beamso that the aspect ratio of the primary beam is controlled, and beamdispersion is minimized upon the primary laser beam exiting theholographic scanning disc 13.

FIG. 4(F) is a schematic illustration of the middle focal plane of theomni-directional scanning pattern produced by the holographic laserscanning system 100-A of the present invention as illustrated in FIGS.4(A), 4(B) and 4(C).

DETAILED DESCRIPTION

Referring to the figures in the accompanying Drawings, the variousillustrative embodiments of the improved laser scanning system (andcomponents therein) of the present invention will be described in greatdetail, wherein like elements will be indicated using like referencenumerals.

FIG. 1 is a schematic illustration of a 3-D omni-directional holographiclaser scanning system 100 including a laser light source 101 (such as aVLD) that emits laser light beams (denoted I). A holographic laserscanning subsystem 103 utilizes a plurality of holographic opticalelements (preferably supported on a rotating disc) to direct portions(denoted I′) of these laser light beams thereby creating anomni-directional scan pattern that defines a 3-D scanning volume 105.Portions of returning (i.e., incoming) returning light rays (denoted I″)from the 3-D scanning volume 105, which reflect off light reflectivesurfaces in the 3-D scanning volume 105, are collected by the opticalsubsystem 103 and portions (denoted I′″) of these returning light raysare directed to photodetector(s) 107 and signal processing and controlcircuitry 109 that capture and analyze the returning laser light rayportions to identify properties (such as bar code symbols and/or images)of surfaces (or objects) within the 3-D scanning volume 105. Preferably,the omni-directional scan pattern produced by the holographic laserscanning system 100 includes different multi-directional scan patternsat varying focal zones (e.g., focal planes) within the 3-D scanningvolume 105. Moreover, such multiple focul zones may cover a depth offield greater than one foot (and preferably cover a depth of fieldgreater than one meter). In addition, the 3-D scanning volume 105 of theomni-directional scan pattern produced by the holographic laser scanningsystem 100 is preferably well-defined (for example, characterized by awell-defined boundary comprised of substantially planar polygonalsurfaces as illustrated in FIGS. 2(A) and 2(B)).

In a preferred embodiment, the improved omni-directional holographiclaser scanning system of the present invention includes a mechanism forautomatically generating visible indicia (i.e., visible scanning-zoneindicators) characterizing the location of the 3-D scanning volume (andthe 3-D omni-directional scanning pattern therein), and thus serving tohelp the user navigate the manual transport of a package therethroughduring automatic identification (Auto-ID) operations carried out in awork environment. In general, the production of visible scanning zoneindicators may be realized by using one or more visible light beams(visibly discernable to users of the system) which provide a visiblelight pattern characterizing the location of the 3-D scanning volume(and the 3-D omni-directional scanning pattern therein) generated by thesystem.

Alternatively, although less preferable in particular applications, suchvisible indicia may be realized by visible markings (visibly discernableto users of the system), such as reflective paint or reflective tape,affixed to a surface beneath the omni-directional 3-D laser scanningsystem and in such a manner that characterizes location of the 3-Dscanning volume (and the 3-D omni-directional scanning pattern therein)of the system.

Such scanning-zone indicators may specify the location of the 3-Dscanning volume (and the 3-D omni-directional scanning pattern therein)by providing an indication of the approximate location of the center ofthe 3-D scanning volume, of one or more edges of the 3-D scanningvolume, and/or of any other portion of the scanning volume. Such visibleindicia enable users to quickly identify the correct location of the 3-Domni-directional scan pattern therein when attempting to transport theobject through the 3-D scanning volume, thus limiting unwanted scanningerrors and increasing the productivity of the user, which representsdecreased costs associated with the use of the system. Moreover, suchfeatures can potentially avoid repetitive motion strain and injury dueto users repetitively searching for location of the 3-D scanning volumeduring manual transport of a package therethrough during automaticidentification (Auto-ID) operations carried out in a work environment.

FIGS. 2(A) and (B) illustrate an exemplary embodiment of an overhead(i.e. walk-under) 3-D omni-directional holographic laser scanning system100′ according to the present invention which includes a mechanism forautomatically generating one or more visible light beams (for example, 4visible light beams 111A, 111B, 111C and 111D as shown) that produce avisible light pattern (i.e. scanning-zone indicator pattern) whichcharacterizes the location (and general spatial boundaries) of a 3-Dscanning volume 105′ (and the 3-D omni-directional scanning patterntherein) generated from the system 100′. In this walk-underconfiguration, the 3-D omni-directional holographic laser scanningsystem 100′ is stationarily mounted above a work environment. The 3-Dscanning volume (and the 3-D omni-directional scanning pattern therein)projects downward toward a surface to scan objects (e.g., packages) thatare moved under human control over the surface.

In this configuration, the visible light pattern produced by the visiblelight beams may characterize location (and general spatial boundaries)of the 3-D scanning volume (and the 3-D omni-directional scanningpattern therein) by providing an indication of the approximate locationof the edges of the 3-D scanning volume (and the 3-D omni-directionalscanning pattern therein) as shown. In addition, the shining of thevisible light pattern onto the surface 113 over which the objects (e.g.,packages) are manually transported by a human through the 3-D scanningvolume 105′ provides a visible indication of points substantiallycorresponding to the boundary of the projection of the 3-D scanningvolume 105′ (and the 3-D omni-directional scanning pattern therein) ontothe surface 113. Alternatively, the visible light pattern produced bythe one or more visible light beams may characterize location (andgeneral spatial boundaries) of the 3-D scanning volume (and the 3-Domni-directional scanning pattern therein) by providing an indication ofthe approximate location of the center of the 3-D scanning volume and/orof any other portion of the 3-D scanning volume of the system 100′.

As shown in FIG. 2(B), the visible light beams may be produced by one ormore light production modules (for example, 4 light production modules115A, 115B, 115C, 115D) mounted to the exterior bottom of the housing ofthe overhead holographic laser scanning system 100′. Alternatively, thelaser light production modules may be mounted within the interior of thehousing of the overhead holographic laser scanning system and projectthrough a window in the housing. The one or more light productionmodules produce and direct at least one visible light beam (for example,the 4 visible light beams 111A, 111B, 111C and 111D as shown) to therebyconstruct the visible light pattern characterizing location of the 3-Dscanning volume 105′ (and the 3-D omni-directional scanning patterntherein) below the laser scanning system 100′. The light productionmodules may utilize a visible laser light source (such as a VLD), alight-emitting diode or a white light source to generate the visiblelight. Preferably, the one or more visible light beams that make up thevisible light pattern are distinguishable by brightness, color or bothwith respect to the laser light used by the laser scanning system 100′in scanning the 3-D scanning volume 105′.

In this illustrative embodiment, the system 100′ may utilize collimating(e.g., focusing) elements and possibly other optical elements togenerate and direct visible light to thereby produce the visible lightpattern constituting the scanning zone indictors which help humanoperators accurately navigate packages and other bar-coded objectsthrough the 3-D scanning volume during package transport operations. Forexample, multiple visible light beams-may be generated by a singlevisible light source in cooperation with a beam splitter.

In addition, the one or more visible light beams that make up thevisible light pattern may be pulsed (for aiding its visibility or forcompliance with laser safety standards). In such instances, the visiblelight beams are preferably pulsed at a frequency less than the criticalflicker frequency to improve the visibility of the visible light patternto potential users. The critical flicker frequency is the point at whichthe one or more flickering visible light beam are no longer perceived asperiodic but shifts to continuous.

In this illustrative embodiment, the 3-D omni-directional holographiclaser scanning may utilize one or more laser light sources (e.g., VLDs)having characteristic wavelength(s) in producing the omni-directionallaser scanning beams together with one or more matched optical filtersthat enable such characteristic wavelength(s) of light to passtherethrough to the photodetector(s) 107 (while substantially blockinglight outside such characteristic wavelength(s) from reaching thephotodetector(s) 107), thereby minimizing the ambient noise that reachesthe phototdetector(s) 107. Such ambient noise, if left unblocked,potentially may interfere with the signal processing functions (and,possibly the bar-code symbol decoding functions) applied to the outputof the phototdetector(s) 107. In such a system, in the event that one ormore laser light sources (e.g., VLDs) are used to generate the visiblelight pattern that characterizes location of the 3-D scanning volume(and the 3-D omni-directional scanning pattern therein), thecharacteristic wavelength of such laser light sources (e.g. VLDs) ispreferably different from the characteristic wavelength(s) of the laserlight source(s) used to produce the 3-D omni-directional scanningpattern. With this design, the optical filters will substantially blockany noise produced from the laser light sources (e.g., VLDs) that areused to generate the visible light beams that characterize location ofthe 3-D scanning volume (and the 3-D omni-directional scanning patterntherein) from reaching the photodetector(s) 107), thereby minimizing thenoise that reaches the phototdetector(s) 107.

FIG. 3 illustrates an exemplary embodiment of an overhead 3-Domni-directional holographic laser scanning system 100″ according to thepresent invention including visible markings 112 affixed to a surface113 over which the objects are moved. Such visible markings 112characterize location (and general spatial boundaries) of the 3-Dscanning volume 105″ (and the 3-D omni-directional scanning patterntherein), for example, by providing an indication of the approximatelocation of the edges of the 3-D scanning volume 105″ as shown.Alternatively, such visible markings 112 may characterize location (andgeneral spatial boundaries) of the 3-D scanning volume 105″ (and the 3-Domni-directional scanning pattern therein) by providing an indication ofthe approximate location of the center of the 3-D scanning volume 105″and/or of any other portion of the 3-D scanning volume 105″. Suchvisible markings 112 may be visible tape (such as reflective or brightcolored tape) or may be visible paint (such as reflective or brightcolored paint) applied to the surface 113.

In another embodiment of the 3-D omni-directional holographic laserscanning system of the present invention, the laser scanning beam(s)used by the system to detect properties (such as bar-code symbolsaffixed thereto) of surfaces passing through the 3-D scanning volume maybe used to provide such visible indicia. For example, such visibleindicia may be provided by controlling the 3-D omni-directionalholographic laser scanning system to repeatably scan select scan linesthat pass through the 3-D scanning volume thereby providing a pulsing ofsuch select scan lines in a manner that provides a characterization oflocation (and general spatial boundaries) of the 3-D scanning volume(and the 3-D omni-directional scanning pattern therein) that is visiblydiscernable to users of the system. The pulsing of such select scanlines may characterize location (and general spatial boundaries) of the3-D scanning volume (and the 3-D omni-directional scanning patterntherein) by providing an indication of the approximate location of thecenter of the 3-D scanning volume, of one or more edges of the 3-Dscanning volume, and/or of any other portion of the 3-D scanning volume.

The 3-D omni-directional holographic laser scanning system of thepresent invention may utilize holographic scanning discs supportingholographic optical elements in generating the omni-directional scanningpattern, as taught in WIPO patent application Publication No. WO98/22945, herein incorporated by reference in its entirety. An exemplaryholographic laser scanning system 100-A of the present invention isillustrated in detail in FIGS. 4(A)-(F). Preferably, theomni-directional scan pattern produced by the holographic laser scanningsystem 100-A includes different multi-directional scan patterns atvarying focal zones (e.g., focal planes) within the 3-D scanning volume.Moreover, such multiple focul zones may cover a depth of field greaterthan one foot (and preferably cover a depth of field greater than onemeter). In addition, the 3-D scanning volume of the omni-directionalscan pattern (produced by the holographic laser scanning system 100-A)is preferably characterized by a well-defined boundary comprised ofsubstantially planar polygonal surfaces (as illustrated in FIGS. 2(A)and 2(B)).

The exemplary holographic laser scanning system utilizes multi-facetedholographic optical elements to direct a 3-D omni-directional scanpattern of outgoing laser light through the 3-D scanning volume andcollect the incoming light for capture by the optical detector(s). The3-D scanning volume contains an omni-directional laser scanning patternhaving different scan patterns over five focal zones, which are formedby five laser scanning stations indicated as LS1, LS2, LS3, LS4 and LS5in FIG. 4(A), arranged about a sixteen-facet holographic scanning disc130 (illustrated in greater detail in FIG. 4(D)). The scanning patternprojected within the middle (third) focal zone (e.g., focal plane) ofthe holographic laser scanning system is shown in FIG. 4(F).

In general, the scan pattern and scan speeds for the holographic laserscanning system can be designed and constructed using the methodsdetailed in U.S. Pat. Nos. 6,158,659, 6,085,978, 6,073,846, and5,984,185, all commonly assigned to the assignee of the presentinvention and each herein incorporated by reference in their entirety.The design parameters for each sixteen facet holographic scanning discshown in FIG. 4(D), and the supporting subsystems used therewith, areset forth in detail in the above-referenced US Patents.

As described in WIPO Patent Application Publication No. WO 98/22945, theholographic laser scanning system 100-A employed herein cyclicallygenerates from its compact scanner housing 140 shown in FIG. 4(A), acomplex three-dimensional laser scanning pattern within a well defined3-D scanning volume. In this illustrative embodiment, such laserscanning pattern is generated by a rotating holographic scanning disc130, about which are mounted five (5) independent laser scanningstations, sometime referred to as laser scanning modules by Applicants.In FIG. 4(A), these laser scanning stations are indicated by LS1, LS2,LS3, LS4 and LS5.

In FIG. 4(B), one of the laser scanning stations in the holographicscanning system 100-A is shown in greater detail. For illustrationpurposes, all subcomponents associated therewith shall be referencedwith the character “A”, whereas the subcomponents associated with theother four laser scanning stations shall be referenced using thecharacters B through E. As illustrated in FIG. 5(B), a beam foldingmirror 142A associated with the laser scanning station L1, has asubstantially planar reflective surface and is tangentially mountedadjacent to the holographic scanning disc 130. In the illustrativeembodiment, beam folding mirror 142A is supported in this positionrelative to the housing base (i.e. the optical bench) 143 using supportlegs 144A and 145A and rear support bracket 146A.

As shown in FIG. 4(B), the laser scanning station L1 includes a laserbeam production module 147A mounted on the optical bench (i.e. housingbase plate 143). The laser beam production module 147A is preferablymounted on the optical bench 143 immediately beneath its associated beamfolding mirror 142A.

As shown in FIG. 4(A), the five laser production modules 142A through142E are mounted on base plate 143, substantially but not exactlysymmetrically about the axis of rotation of the shaft of electric motor150. During laser scanning operations these laser beam productionmodules produce 5 independent laser beams which are directed through theedge of the holographic disc 130 at an angle of incidence A_(i), which,owing to the symmetry of the laser scanning pattern of the illustrativeembodiment, is the same for each laser scanning station (i.e. A_(i)=43.0degrees for all values of i). The incident laser beams produced from the5 laser beam production modules 142A through 142E extend along the fivecentral reference planes, each extending normal to the plane of baseplate 143 and arranged about 72 degrees apart from its adjacentneighboring central planes. While these central reference planes are notreal (i.e. are merely virtual), they are useful in describing thegeometrical structure of each laser scanning station in the holographiclaser scanning system 100-A of the present invention.

The facets of rotating the scanning disk 130 diffract the incident lightbeams (produced from the laser beam production modules 147A . . . 147E)and directs the diffracted light beams onto the associated light bendingmirrors 142A . . . 142E, which directs the diffracted light beamsthrough the 3-D scanning volume, thereby producing a 3-Domni-directional scanning pattern. The middle (third) focal zone (i.e.,focal plane) of this 3-D omni-directional scanning pattern is shown inFIG. 4(F).

As shown in FIG. 4(B), the laser scanning station L1 includes at leastone photodetector (e.g. a silicon photocell) 152A mounted along itscentral reference plane, above the holographic disc 130 and opposite itsassociated beam folding mirror 142A so that it does not block orotherwise interfere with the returning (i.e. incoming) light raysreflecting off light reflective surfaces (e.g. product surfaces, barcode symbols, etc) during laser scanning and light collectingoperations.

In the illustrative embodiment, the photodetectors 152A through 152E aresupported in their respective positions by a photodetector support frame153, which is stationarily mounted to the optical bench by way ofvertically extending support elements (two shown as 154A and 154B). Theelectrical analog scan data signal produced from each photodetector 152Athrough 152E is processed in a conventional manner by its analog scandata signal processing circuitry 201A through 201E, which may besupported upon the photodetector support frame as shown. The analog scandata signal processing circuitry 201A may be realized as an ApplicationSpecific Integrated Circuit (ASIC) chip, which is suitably mounted withthe photodetector 152A onto a small printed circuit (PC) board, alongwith electrical connectors which allow for interfacing with other boardswithin the scanner housing. With all of its components mounted thereon,each PC board may be suitably fastened to the photodetector supportframe 153, along its respective central reference frame, as shown inFIG. 5(B).

Notably, the height of the photodetector support frame 153, referencedto the base plate (i.e. optical bench), is chosen to be less than theminimum height so that the beam folding mirrors must extend above theholographic disc in order to realize the pre-specified laser scanningpattern of the illustrative embodiment. In practice, this heightparameter is not selected (i.e. specified) until after the holographicdisc has been completely designed according to the design process of thepresent invention, while satisfying the design constraints imposed onthe disc design process. As explained in detail in WIPO PatentApplication Publication No. WO 98/22945, the use of a spreadsheet-typecomputer program to analytically model the geometrical structure of boththe laser scanning apparatus and the ray optics of the laser beamscanning process, allows the designer to determine the geometricalparameters associated with the holographic scanning facets on the discwhich, given the specified maximum height of the beam folding mirrorsY_(j), will produce the pre-specified laser scanning pattern (includingfocal plane resolution) while maximizing the use of the available lightcollecting area on the holographic scanning disc.

As best shown in FIG. 4(C), the parabolic light collecting mirror 149Aof the laser scanning station L1 is disposed beneath the holographicscanning disc 130, along the central reference plane associated with thelaser scanning station. While certainly not apparent from this figure,precise placement of the parabolic light collecting element (e.g.mirror) 149A relative to the holographic facets on the scanning disc 130is a critical requirement for effective light detection by thephotodetector (152A) associated with each laser scanning station L1.Placement of the photodetector 152A at the focal point of the paraboliclight focusing mirror alone is not sufficient for optimal lightdetection in the light detection subsystem of the present invention. Astaught in WIPO Patent Application Publication No. WO 98/22945, carefulanalysis must be accorded to the light diffraction efficiency of theholographic facets on the scanning disc and to the polarization state(s)of collected and focused light rays being transmitted therethrough fordetection. As will become more apparent hereinafter, the purpose of suchlight diffraction efficiency analysis ensures the realization of twoimportant conditions, namely: (i) that substantially all of the incominglight rays reflected off an object (e.g. surface, or bar code symbolaffixed thereto) and passing through the holographic facet (producingthe corresponding instant scanning beam) are collected by the paraboliclight collecting mirror 149A; and (ii) that all of the light rayscollected by the parabolic light collecting mirror 149A are focusedthrough the same holographic facet onto the photodetector associatedwith the station, with minimal loss associated with light diffractionand refractive scattering within the holographic facet. A detailedprocedure is described in WIPO Patent Application Publication No. WO98/22945 for designing and installing the parabolic light collectingmirror 149A in order to satisfy the operating conditions for effectivelight collection and detection as described above.

The optical scan data signal D₀ focused onto the photodetector 152Aduring laser scanning operations is produced by light rays of aparticular polarization state (e.g., S polarization state) associatedwith a diffracted laser beam being scanned across a light reflectivesurface (e.g. the bars and spaces of a bar code symbol) and scatteringthereof. Typically, the polarization state distribution of the scatteredlight rays is altered when the scanned surface exhibits diffusereflective characteristics. Thereafter, a portion of the scattered lightrays are reflected along the same outgoing light ray paths toward theholographic facet(s) on the scanning disc 130 which produced the scannedlaser beam. These reflected light rays are collected by these facet(s)and ultimately focused onto the photodetector 152A by its paraboliclight reflecting mirror 149A disposed beneath the scanning disc 130. Thefunction of each photodetector 152A is to detect variations in theamplitude (i.e. intensity) of optical scan data signal D₀, and toproduce in response thereto an electrical analog scan data signal D₁which corresponds to such intensity variations. When a photodetectorwith suitable light sensitivity characteristics is used, the amplitudevariations of electrical analog scan data signal D₀ will linearlycorrespond to the light reflection characteristics of the scannedsurface (e.g. the scanned bar code symbol). The function of the analogsignal processing circuitry 201A is to filter and amplify the electricalanalog scan data signal D₀, in order to improve the signal-to-noiseratio (SNR) of the signal D₁ for output to digital signal processingcircuitry, which is preferably mounted on PC board 202A that is disposedbehind the beam folding mirror 142A of the laser scanning station L1 asshown in FIG. 4(C).

The digital signal processing circuitry, which is preferably mounted onthe PC board 202A as shown in FIG. 4(C), preferably operates to convertthe analog scan data signal D₁ output by the-analog signal processingcircuitry into a corresponding digital scan data signal D_(2,) andprocesses the digital scan data signal D₂ to extract information (suchas symbols or bar codes) related to surfaces of objects passing throughthe 3-D scanning volume based upon the characteristics of the reflectedlight encoded by the digital scan data signal D₂.

The digital signal processing circuitry preferably includes A/Dconversion circuitry that converts the analog scan data signal D₁ outputby the analog signal processing circuitry into a corresponding digitalscan data signal D₂ having first and second (i.e. binary) signal levelswhich correspond to the bars and spaces of the bar code symbol beingscanned. Preferably, the A/D conversion circuitry performs athresholding function on a second-derivative zero-crossing signal ingenerating the digital scan data signal D₂. In practice, the digitalscan data signal D₂ appears as a pulse-width modulated type signal asthe first and second signal levels thereof vary in proportion to thewidth of bars and spaces in the scanned bar code symbol.

In addition, the digital signal processing circuitry includes digitizingcircuitry whose functions are two-fold: (1) to convert the digital scandata signal D₂, associated with each scanned bar code symbol, into acorresponding sequence of digital words (i.e. a sequence of digitalcount values) D₃ representative of package identification (I.D.) data;and (2) to correlate time-based (or position-based) information aboutthe facet sector on the scanning disc 130 that generated the sequencedigital words D₃ (corresponding to a scan line or portion thereof).

Notably, in the digital word D₃, each digital word represents the timelength duration of first or second signal level in the correspondingdigital scan data signal D₂. Preferably, the digital words D₃ are in adigital format suitable for use in carrying out various symbol decodingoperations which, like the scanning pattern and volume of the presentinvention, will be determined primarily by the particular scanningapplication at hand.

In addition, the digital signal processing circuitry includes symboldecoding circuitry that primarily functions to receive the digital wordsequence D₃ produced from its respective digitizing circuitry, andsubject it to one or more bar code symbol decoding algorithms in orderto determine which bar code symbol is indicated (i.e. represented) bythe digital word sequence D₃.

Reference is made to U.S. Pat. No. 5,343,027 to Knowles, hereinincorporated by reference in its entirety, as it provides technicaldetails regarding the design and construction of circuitry suitable foruse in the holographic laser scanning system 100-A of the presentinvention.

In addition, the digital signal processing circuitry may generateinformation that specifies a vector-based geometric model of the laserscanning beam (and possibly plane-sector) that was used to collect thescan data underlying the decode bar code symbol. Such information may beused with “3-D ray tracing techniques” to derive the position of thedecoded bar code symbol in the 3-D scanning volume as described indetail in co-pending U.S. patent application Ser. No. 09/157,778, filedSep. 21, 1998, co-pending U.S. patent application Ser. No. 09/327,756filed Jun. 7, 1999, and International Application PCT/US00/15624, filedJun. 7, 2000, all commonly assigned to the assignee of the presentinvention and herein incorporated by reference in their entirety.

In addition, the analog (or digital) signal processing circuitry mayinclude a plurality of pass-band filter stages corresponding todifferent focal zones (or different scan ranges) in the 3-D scanningvolume. Each pass-band filter stage is designed with particular high(and low) cut-off frequencies that pass the spectral components of theanalog scan data signal produced when a bar code symbol is scanned atthe corresponding focal zone (or scan range), while limiting noiseoutside the particular spectral pass-band of interest. When a bar codesymbol is scanned by a laser beam focused within a particular focal zonein the 3-D scanning volume, the pass-band filter stage corresponding tothe particular focal zone (or particular scan range) is automaticallyswitched into operation so that the spectral components of the analogscan data signal within the particular spectral pass-band are present,while noise outside the particular spectral pass-band is limited. Thisselective filtering enables the signal processing circuitry to generatefirst and second derivative signals (which are processed to produce acorresponding digital scan data signal as described above) that aresubstantially free from the destructive effects of thermal and substratenoise that are outside the spectral pass-band of interest for the barcode symbol being scanned. A more detailed description of such selectivefiltering mechanisms (and laser scanning systems that employ suchmechanisms) is described in U.S. patent application Ser. No. 09/243,078filed Feb. 2, 1999, and U.S. application Ser. No. 09/442,718 filed Nov.18, 1999, herein incorporated by reference in their entirety.

FIG. 4(E) illustrates an exemplary embodiment of the laser productionmodules 147A of FIGS. 4(B) and 4(C) including: a visible laser diode(VLD) 101A, an aspheric collimating lens 51 supported within the bore ofa housing 53 mounted upon the optical bench 143 of the module housingfor collimating (e.g., focusing) the laser light produced by the VLD101A; a mirror 55, supported within the housing 53, for directing thefocused laser light produced by lens 51 to a multi-function lightdiffractive grating 57 (sometimes referred to by Applicants as“multi-function HOE” or “multi-function plate”) supported by the housing53. The multi-function light diffractive grating 57, having a fixedspatial frequency and disposed at incident angle relative to theoutgoing laser beam provided by the mirror 55, produces a primary beamthat is directed toward the facets of the rotating scanning disk 130.The multi-function light diffractive grating 57 changes the propertiesof the incident laser beam so that the aspect ratio of the primary beamis controlled, and beam dispersion is minimized upon the primary laserbeam exiting the holographic scanning disc 130. Details for designingthe multi-function light diffractive grating 57 and configuring thelaser scanning beam module 147A of the illustrative embodiment isdescribed in great detail in Applicants” prior U.S. patent applicationSer. No. 08/949,915 filed Oct. 14, 1997, and incorporated herein byreference, incorporated herein by reference in its entirety.

In addition, the holographic laser scanning system 100-A includes laserdrive circuitry (not shown) which generates the electrical signals fordriving the VLD 101A of the respective laser beam production modules147A, 147B, . . . 147E. The laser drive circuitry for a respective VLDmay be disposed on the PC board 202 (shown in FIG. 4(C) as PC board 202Afor the VLD 101A in laser beam production module 147A).

In addition, the holographic laser scanning system 100-A preferablyincludes a control board (not shown) disposed with the housing 140 ontowhich is mounted a number of components mounted on a small PC board,namely: a programmed controller with a system bus and associated programand data storage memory, for controlling the system operation of theholographic laser scanner system 1090A and performing other auxiliaryfunctions; serial data channels (for example, RS-232 channels) forreceiving serial data input from the symbol decoding circuitry describedabove; an input/output (I/O) interface circuit 248 for interfacing withand transmitting symbol character data and other information to an I/Osubsystem (which may be operably coupled to a data management computersystem); home pulse detector, including a photodetector and associatedcircuitry, for detecting the home pulse generated when the laser beamfrom a VLD (in home pulse marking sensing module) is directed throughhome-pulse gap 260 (for example, between Facets Nos. 6 and 7 on thescanning disk 130 as shown in FIG. 4(D)) and sensed by thephotodetector; and a home-offset-pulse (HOP) generator, which ispreferably realized as an ASIC chip, for generating a set of home-offsetpulses (HOPs) in response to the detection of each home pulse by thehome pulse detector. The programmed controller produces motor controlsignals, and laser control signals during system operation that enablemotor drive circuitry to drive the scanning disc motor coupled toholographic scanning disc 130 and enable the laser drive circuitry todrive the VLDs of the laser beam production modules 247A, 247B, . . .247E, respectively. A more detailed description of the control board andits respective components are disclosed in co-pending U.S. patentapplication Ser. No. 09/047,146 filed Mar. 24, 1998, co-pending U.S.patent application Ser. No. 09/157,778, filed Sep. 21, 1998, co-pendingU.S. patent application Ser. No. 09/327,756 filed Jun. 7, 1999,co-pending U.S. patent application Ser. No. 09/551,887 filed Apr. 18,2000, International Application No. PCT/US99/06505 filed Mar. 24, 1999,and International Application PCT/US00/15624, filed Jun. 7, 2000, allcommonly assigned to the assignee of the present invention and hereinincorporated by reference in their entirety.

According to the present invention, the holographic laser scanningsystem 100-A includes visible indicia characterizing location (andgeneral spatial boundaries) of the 3-D scanning volume (and the 3-Domni-directional scan pattern therein) that is visibly discernable tousers of the holographic laser scanning system. Such visible indicia maybe one or more visible light beams (visibly discernable to users of theholographic laser scanning system) that provide a visible light patterncharacterizing location (and general spatial boundaries) of the 3-Dscanning volume (and the 3-D omni-directional scan pattern therein).Alternatively, such visible indicia may be visible markings (visiblydiscernable to users of the holographic laser scanning system), such asreflective paint or reflective tape, affixed to a surface (over whichobjects are moved through the 3-D scanning volume) in a manner thatcharacterizes location (and general spatial boundaries) of the 3-Dscanning volume (and the 3-D omni-directional scan pattern therein).Such visible indicia may characterize location (and general spatialboundaries) of the 3-D scanning volume (and the 3-D omni-directionalscan pattern therein) by providing an indication of the approximatelocation of the center of the 3-D scanning volume, of one or more edgesof the 3-D scanning volume, and/or of any other portion of the 3-Dscanning volume. A more detailed description of such mechanisms isdescribed above with respect to FIGS. 2(A), 2(B) and 3. Such visibleindicia enable users to quickly identify the correct location of the 3-Dscanning volume (and the 3-D omni-directional scan pattern therein) whenattempting to transport the object through the 3-D scanning volume, thuslimiting unwanted scanning errors and increasing the productivity of theuser, which represents decreased costs associated with the use of theholographic laser scanning system.

In another embodiment of the 3-D omni-directional holographic laserscanning system of the present invention, such visible indicia may begenerated by controlling the system to repeatably scan select scan linesthat pass through the 3-D scanning volume thereby providing a pulsing ofsuch select scan lines in a manner that provides a characterization oflocation (and general spatial boundaries) of the 3-D scanning volume(and the 3-D omni-directional scan pattern therein) that is visiblydiscernable to users of the system. The pulsing of such select scanlines may characterize location (and general spatial boundaries) of the3-D scanning volume (and the 3-D omni-directional scan pattern therein)by providing an indication of the approximate location of the center ofthe 3-D scanning volume, of one or more edges of the 3-D scanningvolume, and/or of any other portion of the 3-D scanning volume. In theillustrative holographic laser scanning system 100-A as described above,the home pulse detector (and timing signals derived therefrom) may beused to control the pulsing of select scan lines in a manner thatprovides a characterization of location of the 3-D scanning volume (andthe 3-D omni-directional scan pattern therein) that is visiblydiscernable to users of the system.

The improved 3-D omni-directional holographic laser scanning system ofthe illustrative embodiments of the present invention as set forth abovemay include an additional mechanism that indicates when a user entersthe 3-D scanning volume (or a region proximate thereto) and provides theuser with visible (or audio) feedback in response thereto. Such amechanism may employ one or more infra-red detection beams that sweepthe 3-D scanning volume to detect when a user enters the 3-D scanningvolume (or a region proximate thereto). Upon detection, the mechanismgenerates a visual signal (such as flashing light) and/or an audiosignal that indicates that the user is inside (or outside) the 3-Dscanning volume (or the region proximate thereto). In the event that thesystem employs a “good read” audio (and/or visual) indicator, such “goodread” indicator is preferably distinguishable from the signals thatindicate that the user is inside (or outside) the 3-D scanning volume(or the region proximate thereto). In addition, the mechanism thatindicates when a user enters the 3-D scanning volume (or a regionproximate thereto) may be used to selectively activate (or deactivate)generation of the visible light pattern that characterizes location ofthe 3-D scanning volume (and the 3-D omni-directional scanning patterntherein) in response thereto.

The improved 3-D omni-directional holographic laser scanning system ofthe illustrative embodiments of the present invention as described abovecan be used in various types of applications, such as for example, inpackage handling applications where bar codes are read to determine (a)identification of incoming packages, (b) identification of outgoingpackage, and (c) to provide user instructions in manually routing andsorting packages based upon the information encoded by the bar codes.Moreover, the laser scanning system of the illustrative embodiments ofthe present invention as described above can read virtually any bar codesymbology imaginable (e.g. Interleaved two of five, Code 128 and Codethree of nine) and formats so as to sort and identify packages atvarious package rates required by USPS or other end-users, ZIP Codes(six digits), Package Identification Codes (PIC) (sixteen characters)and Tray bar code (ten digits) symbols.

For example, the housing of the improved 3-D omni-directionalholographic laser scanning system of the illustrative embodiments asdescribed above may be mounted to a base that can be moved (and locked)into different spatial positions overhead one or more manual packagescanning, sorting and routing stations (e.g., a station at the end of aslide, a station adjacent a conveyor belt, a station adjacent atransport container or bin, or a station adjacent a transport vehiclesuch as truck or van). It is contemplated that a rolling track or amulti-cantilever arm (similar to the arm used to position a light in adentist's office) may be used to move (and lock) the 3-Domni-directional holographic laser scanning system into the desiredspatial position overhead such stations.

Moreover, the improved 3-D omni-directional holographic laser scanningsystem of the illustrative embodiments of the present invention asdescribed above can process all types of products (e.g. trays and tubshaving extremely large variance in surface types, colors, and plastics(e.g. Tyvek material, canvass, cardboard, polywrap, Styrofoam, rubber,dark packages). Some of these product types include: soft pack pillows,bags; packages having non-flat bottoms, such as flats, trays, and tubswith and without bands; cartons; rugs; duffel bags (without strings ormetal clips); tires; wooden containers; and sacks.

It is understood that the laser scanning systems, modules, engines andsubsystems of the illustrative embodiments may be modified in a varietyof ways which will become readily apparent to those skilled in the art,and having the benefit of the novel teachings disclosed herein. All suchmodifications and variations of the illustrative embodiments thereofshall be deemed to be within the scope and spirit of the presentinvention as defined by the Claims to Invention appended hereto.

1-41. (canceled)
 42. A method of automatically identifying packagesduring manual package sortation operations, comprising the steps of: (a)supporting a laser scanning system above a workspace environment of 3-Dspatial extent occupied by a human operator involved in the manualsortation of packages bearing bar code symbols, said laser scanningsystem including a housing having a light transmission aperture, and alaser scanning pattern generator disposed within said housing; (b)projecting from said laser scanning pattern generator, and through saidlight transmission aperture, a laser scanning pattern substantiallyconfined within the spatial extent of a predefined 3-D scanning volumeand spatially encompassing a substantial portion of said workspaceenvironment; (c) projecting from a visible scanning-zone indicationpattern generator, a visible scanning-zone indication pattern onto afloor surface immediately beneath said workspace environment so as toprovide a visible indication of points substantially corresponding tothe boundary of the projection of said laser scanning pattern onto saidfloor surface; (d) said human operator using said visible scanning-zoneindication pattern to help guide the transport of a package bearing abar code symbol through said predefined 3-D scanning volume so that saidlaser scanning pattern automatically reads the bar code symbol on saidpackage, and said laser scanning system automatically produces symbolcharacter data representative of said read bar code symbol and theidentity of said package; and (e) manually sorting said packageidentified during step (d) within said workspace environment.
 43. Themethod of claim 42, wherein step (b) further comprises: projectinganomnidirectional laser scanning pattern from said laser scanningpattern generator, wherein said omnidirectional laser scanning patternfurther comprises a plurality of focal planes definable relative to saidhousing, and said omnidirectional laser scanning pattern consists of aplurality of scanlines disposed within each said focal plane forscanning the bar code symbol on said package as said package istransported through said predefined 3-D scanning volume.
 44. The methodof claim 42, wherein step (a) comprises supporting said laser scanningsystem above said workspace environment, wherein said laser scanningpattern generator includes: a plurality of laser beam sources forproducing a plurality of laser beams; a holographic scanning disc,rotatable about an axis of rotation, and supporting a plurality ofholographic optical elements for scanning and focusing said plurality oflaser beams so as to produce a plurality of scanning planes; a pluralityof beam folding mirrors disposed about said holographic scanning disc,for folding said plurality of scanning planes so as to project anomnidirectional laser scanning pattern through said light transmissionaperture and within the spatial extent of said predefined 3-D scanningvolume; a plurality of light focusing elements disposed beneath saidholographic scanning disc, each said light focusing element focusingtowards a focal point above said holographic scanning disc, light raysreflected off said scanned bar code symbol and collected by saidholographic optical elements; and a plurality of photodetectors, eachsaid photodetector being proximately disposed at one said focal pointabove said holographic scanning disc, and being radially aligned withthe optical axis of one of said light focusing elements, for directlydetecting the intensity of focused light rays retransmitted through saidholographic optical elements as said holographic scanning disc rotates,and generating a scan data signal for subsequent processing andconversion into said symbol character data.
 45. The method of claim 44,wherein each said light focusing element is realized as a parabolicmirror element.
 46. The method of claim 44, wherein said plurality oflaser beam sources comprises a plurality of visible laser diodes. 47.The method of claim 44, wherein step (c) comprises projecting saidvisible scanning-zone indication pattern from said visible scanning-zoneindication pattern generator which comprises apparatus for producing avisible light pattern that characterizes the spatial location of theboundary of the projection of said omni-directional laser scanningpattern onto said floor surface.
 48. The method of claim 47, whereinduring step (c) said visible light pattern comprises light emitted fromone of at least one white light source, at least one light-emittingdiode, and at least one visible laser diode.
 49. The method of claim 47,wherein during step (c) said visible light pattern is pulsed.
 50. Themethod of claim 49, wherein said visible light pattern is pulsed at afrequency less than the critical flicker frequency.
 51. A system forautomatically identifying packages during manual package sortationoperations, comprising: a laser scanning system supported above aworkspace environment of 3-D spatial extent occupied by a human operatorinvolved in the manual sortation of packages bearing bar code symbols,said laser scanning system including a housing having a lighttransmission aperture, a laser scanning pattern generator disposedwithin said housing, for projecting through said light transmissionaperture a laser scanning pattern substantially confined within thespatial extent of a predefined 3-D scanning volume that spatiallyencompasses a substantial portion of said workspace environment occupiedby said human operator, and a visible scanning-zone indication patterngenerator for projecting a visible scanning-zone indication pattern ontoa floor surface immediately beneath said workspace environment so as toprovide a visible indication of points substantially corresponding tothe boundary of the projection of said laser scanning pattern onto saidfloor surface, wherein said human operator can use said visiblescanning-zone indication pattern to visually guide the transport of apackage bearing a bar code symbol through said predefined 3-D scanningvolume, so that said laser scanning pattern automatically reads the barcode symbol on said package, and said laser scanning systemautomatically produces symbol character data representative of said readbar code symbol and the identity of said package, and thereafter, saidpackage can be manually sorted by said human operator within saidworkspace environment.
 52. The system of claim 51, wherein said laserscanning pattern further comprises a plurality of focal planes definablerelative to said housing, and said laser scanning pattern consists of aplurality of scanlines disposed within each said focal plane forrepeatedly scanning the bar code symbol on said package as said packageis transported through said predefined 3-D scanning volume.
 53. Thesystem of claim 51, wherein said laser scanning pattern generatorcomprises: a plurality of lasers beam sources for producing a pluralityof laser beams; a holographic scanning disc, rotatable about an axis ofrotation, and supporting a plurality of holographic optical elements forscanning and focusing said plurality of laser beams so as to produce aplurality of scanning planes; a plurality of beam folding mirrorsdisposed about said holographic scanning disc, for folding saidplurality of scanning planes so as to project an omnidirectional laserscanning pattern through said light transmission aperture and within thespatial extent of said predefined 3-D scanning volume; a plurality oflight focusing elements disposed beneath said holographic scanning disc,each said light focusing element focusing towards a focal point abovesaid holographic scanning disc, light rays reflected off said scannedbar code symbol and collected by said holographic optical elements; anda plurality of photodetectors, each said photodetector being proximatelydisposed at one said focal point above said holographic scanning disc,and being radially aligned with the optical axis of one of said lightfocusing elements, for directly detecting the intensity of focused lightrays retransmitted through said holographic optical elements as saidholographic scanning disc rotates, and generating a scan data signal forsubsequent processing conversion into said symbol character data. 54.The system of claim 53, wherein each said light focusing element isrealized as a parabolic mirror element.
 55. The system of claim 53,wherein said plurality of laser beam sources comprises a plurality ofvisible laser diodes.
 56. The system of claim 44, wherein said visiblescanning-zone indication pattern generator comprises apparatus forproducing a visible light pattern that characterizes the spatiallocation of the boundary of the projection of said laser scanningpattern onto said floor surface.
 57. The system of claim 56, whereinsaid visible light pattern comprises light emitted from one of at leastone white light source, at least one light-emitting diode, and at leastone visible laser diode.
 58. The system of claim 56, wherein saidvisible light pattern is pulsed.
 59. The system of claim 58, whereinsaid visible light pattern is pulsed at a frequency less than thecritical flicker frequency.